1. Field of the Invention
The present invention relates to a semiconductor cooling device to cool a semiconductor chip such as a semiconductor laser diode or the like, and a stack of semiconductor cooling devices obtained by stacking a plurality of the cooling devices.
2. Related Art
A water cooling type of semiconductor cooling device called a water jacket is mounted on a semiconductor chip such as a semiconductor laser diode or the like that generates heat. The semiconductor chip in use is cooled by the semiconductor cooling device to maintain the function of the semiconductor chip.
For example, JP-A-11-97770 discloses a semiconductor cooling device which is constituted by integrally forming an upper plate, an intermediate plate and a lower plate which are made of copper relying upon a diffusion junction or a solder junction, forming a cooling water inlet portion, a cooling water outlet portion and a cooling water flow passage portion, and permitting the cooling water to flow in through the inlet portion, to flow through the flow passage portion and to flow out from the outlet portion to thereby efficiently cool the semiconductor chip.
However, the plates made of copper have a low rigidity. Therefore, when the semiconductor cooling devices are stacked in a plural number and when the semiconductor laser diodes are mounted on these semiconductor cooling devices in an attempt to obtain an increased laser beam output, the semiconductor cooling devices being coupled together by using bolts, a problem arises in that the semiconductor cooling devices are distorted due to the fastening forces of bolts adversely affecting the directivity of the laser beams. Besides, if the semiconductor cooling device is not stacked, a distortion that happens to occur in the semiconductor cooling device adversely affects the directivity of the laser beam.
Besides, copper which is the material forming the plates, has a high coefficient of thermal expansion which is greatly different from the coefficient of thermal expansion of the material of the semiconductor chip such as gallium arsenide. Due to the heat generated by the semiconductor chip, therefore, there arises a problem in that the. semiconductor chip separates away from the semiconductor cooling device after the passage of time.